Truss-type shear reinforcement material having double anchorage functions at both top and bottom thereof

ABSTRACT

The present invention relates to a shear reinforcement material of a reinforced concrete structure, which is installed in a reinforced concrete structure to increase resistance against shear failure. The truss-type shear reinforcement material having double anchorage functions at both top and bottom thereof is configured by installing double anchor heads on the top and the bottom of a truss ( 20 ), which is formed by connecting an upper member ( 24 ) with a lower member ( 26 ) through connection members ( 21 ) such as vertical members ( 22 ) or inclined members ( 23 ). Therefore, the shear reinforcement material according to the present invention can improve shear resistance, shear reinforcement and ductility, because upper anchor heads ( 34 ) and the upper member ( 24 ) carry out a double anchorage function on the top while lower anchor heads ( 44 ) and the lower member ( 26 ) carry out a double anchorage function on the bottom, and furthermore, improves construction quality as building a concrete structure becomes more convenient.

TECHNICAL FIELD

The present invention relates to a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, and more particularly, to such a truss-type shear reinforcement device of a reinforced concrete structure, which is installed in a reinforced concrete structure to increase resistance against shear failure. The truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof is configured by installing double anchorage at the upper and lower sides of a truss, which is formed by connecting an upper chord member with a lower chord member through connection members such as vertical members or diagonal members, thereby improving shear resistance, shear reinforcement and ductility and improving construction quality while making construction of a concrete structure more convenient.

BACKGROUND ART

In a reinforced concrete structure constructed through application of reinforcing bars and concrete, particularly, slabs, girders or beams, columns, walls, corbels, and the like needs increased shear resistance, and thus, a shear reinforcement device for reinforcement of shear performance is constructed. For example, a shear force greatly acts on a joint (i.e., a column head portion) between the slab and the column along the circumference of the column in the reinforced concrete structure. Thus, if the joint does not have a sufficient shear resistance, there is a great risk of occurrence of shear failure. In particular, in case of the joint between the slab and the column in a flat slab structure in which a large girder or a small beam are not installed but the slab is directly supported by the columns, an excessive stress is intensively concentrated on the slab surrounding the column unlike a general joint between the beam and the column to induce a bidirectional shear failure (or punching shear failure) forming a reversed trapezoidal shape as disclosed in Korean Patent Laid-Open Publication No. 10-2007-0053836 entitled “SHEAR REINFORCEMENT DEVICE FOR COLUM-SLAB JOINTS AND ITS MENUFACTURING METHOD” and Korean Patent Registration No. 10-0676627 entitled “SHEAR REINFORCEMENT DEVICE FOR SLAB-COLUMN JOINTS AND SHEAR REINFORCEMENT STRUCTURE USING THE DEVICE”. Since such a shear failure is very brittle unlike other types of failure patterns, it is greatly critical to stability of the slab-column joints, so that a special attention must be paid to the joints in the structure design and a sufficient measure must be taken to prevent the shear failure from being occurring.

FIG. 1 shows perspective views of shear reinforcement devices used to increase the shear performance of the joints between slabs and columns in a reinforced concrete structure, and FIG. 2 shows views for explaining problems occurring at the time of installation and stress reversal of the shear reinforcement devices shown in FIG. 1.

In this case, FIGS. 1( a) and 2(a) are views for explaining a method which applies a typical stirrup 100 as the shear reinforcement device, and FIGS. 1( b) and 2(b) are views for explaining a method which applies a shear stud 200 as the shear reinforcement device as disclosed in Korean Patent Laid-Open Publication No. 10-2004-0076644 entitled “REINFORCED CONCRETE REINFORCEMENT DEVICE AND METHOD FOR CONSTRUCTING REINFORCED CONCRETE STRUCTURE INCLUDING THE SAME”. In addition, FIGS. 1( c) and 2(c) are views for explaining a method which applies a shear band 300 as the shear reinforcement device as disclosed in Korean Patent Laid-Open Publication No. 10-2007-0053836 entitled “SHEAR REINFORCEMENT DEVICE FOR COLUM-SLAB JOINTS AND ITS MENUFACTURING METHOD” and Korean Patent Registration No. 10-0676627 entitled “SHEAR REINFORCEMENT DEVICE FOR SLAB-COLUMN JOINTS AND SHEAR REINFORCEMENT STRUCTURE USING THE DEVICE”.

Referring to FIGS. 1 and 2, a conventional shear reinforcement method entails a problem in that since the shear reinforcement device (i.e., stirrup 100, shear stud 200 and shear band 300) is deformed at the time of stress reversal, the shear performance is remarkably lowered upon the repeated exertion of the shear stress. Further, the concrete coating thickness during construction must be necessarily taken into consideration, but is difficult to precisely control actually, thus resulting in a problem in that construction defects occur or the performance of the structure is deteriorated. Moreover, since the conventional shear reinforcement devices are difficult for field workers with repetitive motion tasks to install, careful attention must be paid to installation of the shear reinforcement devices and satisfaction of the required design conditions is difficult.

The problems associated with the conventional prior arts will be described hereinafter in more detail. First, the method for using the stirrup 100 as the shear reinforcement device will be described hereinafter in more detail.

Lower main reinforcing bars 5 and upper main reinforcing bars 4 are installed. In this case, although not shown, the upper and lower sub reinforcing bars may be installed in the vicinity of the upper and lower portions of a concrete layer. Then, the upper and lower main reinforcing bars 4 and 5 are surrounded by the stirrup 100 and both ends of the stirrup 100 are tied together on any one of the upper and lower main reinforcing bars 4 and 5. Thus, this makes it difficult to work as well as much working time is spent. As shown in FIG. 2( a), if an upper stress is expanded, there occurs a phenomenon in which the both ends of the stirrup 100 tied together on the main reinforcing bar are widened in a direction of an arrow, and thus the shear performance is remarkably lowered upon the repeated exertion of the shear stress. In addition, as shown in FIG. 2( a), concrete coating thicknesses L1 and L2 are specified from a top surface 2 and an underside surface of a slab 1. Since such a method of using the stirrup 100 requires that the thickness of the stirrup 100 should be taken into consideration, it is difficult to actually satisfy the specified concrete coating thicknesses L1 and L2 due to an error of work. Besides, since the upper and lower main reinforcing bars 4 and 5 and the upper and lower portions of the slab adjacent to the main reinforcing bars 4 and 5 are moved from the top surface 2 and the underside surface 3 of the slab 1, the moment resistance performance of the structure is deteriorated.

Next, the method for using the shear stud 200 as the shear reinforcement device will be described hereinafter in more detail.

The shear stud 200 is configured such that stud bodies are vertically installed on the rail 210 at regular intervals and heads 230 are disposed on the tops of the stud bodies. Thus, the installation work of the shear stud 200 can be expected to be relatively improved as compared to the method for using the stirrup 100 as the shear reinforcement device. The method for using the shear stud 200 as the shear reinforcement device, however, still encounters a problem. That is, as shown in FIG. 2, if an upper stress is expanded, the stud bodies are widened in a direction of the heads 230, and thus the shear performance is lowered upon the repeated exertion of the shear stress. Also, a worker must pay a special attention to satisfy the specified concrete coating thicknesses L1 and L2, and the upper or lower reinforcing bars are moved from the top surface 2 or underside surface 3 of the slab 1, and thus the performance of the structure is deteriorated.

Last, the method for using the shear band 300 as the shear reinforcement device will be described hereinafter in more detail.

As shown in FIG. 1( c), the shear band 300 is configured such that a sheet as disclosed in Korean Patent Laid-Open Publication No. 10-2007-0053836 entitled “SHEAR REINFORCEMENT DEVICE FOR COLUM-SLAB JOINTS AND ITS MENUFACTURING METHOD” or a wire rod as disclosed in Korean Patent Registration No. 10-0676627 entitled “SHEAR REINFORCEMENT DEVICE FOR SLAB-COLUMN JOINTS AND SHEAR REINFORCEMENT STRUCTURE USING THE DEVICE” is bent in a concavo-convex shape. Thus, the installation work of the shear band 300 can be expected to be relatively improved as compared to the method for using the stirrup 100 as the shear reinforcement device. The method for using the shear band 300 as the shear reinforcement device, however, still encounters a problem in that in case of applying the sheet, there occurs an interference between the sheet and the placement of the upper and lower reinforcing bars, making the construction difficult, and in that in case of the sheet, the shear band 300 blocks concrete at the time of pouring of concrete for the slab, thus resulting in defective filling of concrete. In particular, in case of the shear band 300 to which the sheet is applied, there is caused a problem in that the shear band 300 isolates concrete being poured, and thus the strength of the joints between slabs and columns is rather weakened due to isolation of concrete. In addition, the method for using the shear band 300 as the shear reinforcement device still involves a drawback in that it has the same problems as those occurring in the above-mentioned stirrup 100 and shear stud 200, as well as the shear band 300 is widened transversely at the upper and lower sides thereof and upon the expansion of the stress as shown in FIG. 2( c).

DISCLOSURE OF INVENTION Technical Problem

Accordingly, the present invention has been made in an effort to solve the problems occurring in the prior art and it is an object of the present invention to provide a novel truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, which can stably secure the shear performance through a structure for preventing deformation of the shear reinforcement device at the time of stress reversal thereof.

Another object of the present invention is to provide a novel truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, in which the concrete coating thickness can be conformed to a specified value even without taking into consideration the concrete coating thickness at the time of installation of the shear reinforcement device by a worker so that the time required for field workers to install the shear reinforcement device can be reduced and the specified design conditions can be easily satisfied during construction, thereby minimizing construction defects due to installation of the shear reinforcement device and effectively increasing the performance of the structure.

Still another object of the present invention is to provide a novel truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, which is installed in a reinforced concrete structure, particularly at joints where slabs and columns are joined to each other or is installed as a substitute for a stirrup of a beam, a column, a wall, a foundation, and the like to increase resistance against shear failure.

Yet another object of the present invention is to provide a novel truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, which can be installed in a reinforced concrete structure, particularly at joints where slabs and columns are joined to each other or can be installed as a substitute for a stirrup of a beam, a column, a wall, a foundation, and the like, thereby effectively preventing an interference between the shear reinforcement device and the reinforcing bars during the reinforcing bar placement, and maximizing the shear reinforcement range to effectively prevent shear failure occurring at the joints between slabs and columns.

Particularly, a further object of the present invention is to provide a novel truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, which is configured to have a double anchorage structure at upper and lower sides thereof unlike the conventional prior arts, thereby ensuring reliability of strength and ductility against an allowable shear stress of a concrete structure being poured, particularly the joints between slabs and columns even at the time of occurrence of repeated stress reversal due to exertion of a lateral load such as earthquake, and the like, and enhancing lateral load resistance. more effectively.

Technical Solution

To achieve the above objects, according to the features of the present invention, there is provided a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, which is installed in a reinforced concrete structure to increase resistance against shear failure, characterized in that the truss-type shear reinforcement device includes: a truss 20 including an upper chord member 24, a lower chord member 26, and one or more connection members 21 for interconnecting the upper chord member 24 and the lower chord member 26; one or more upper anchor heads 34 fixedly connected with the upper chord member 24 of the truss 20 at the upper side of the truss 20; and one or more lower anchor heads 44 fixedly connected with the lower chord member 26 of the truss 20 at the lower side of the truss 20.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, each of the connection members 21 may include any one of a vertical member 22 and a diagonal member 23. The vertical member 22 may be formed at an upper portion thereof with an upper panel point 31 where the upper chord member 24 and the vertical member 22 are joined to each other, and are formed at a lower portion thereof with a lower panel point 41 where the lower chord member 26 and the vertical member 22 are joined to each other, in such a fashion that the upper panel point 31 and the lower panel point 41 of the vertical member 22 are vertically aligned. In addition, the diagonal member 23 may be formed at an upper portion thereof with an upper panel point 31 where the upper chord member 24 and the diagonal member 23 are joined to each other, and are formed at a lower portion thereof with a lower panel point 41 where the lower chord member 26 and the diagonal member 23 are joined to each other, in such a fashion that the upper panel point 31 and the lower panel point 41 of the diagonal member 23 are diagonally aligned.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, each of the connection members 21 may include an upper spacer 32 protrudingly extending upwardly from the top of the upper chord member 24 by a predetermined distance, and a lower spacer 42 protrudingly extending downwardly from the bottom of the lower chord member 26 by a predetermined distance. In addition, each of the upper anchor heads 34 may be joined to the upper spacer 32 so that it is installed spaced apart by the predetermined distance from the upper chord member 24, and each of the lower anchor heads 44 may be joined to the lower spacer 42 so that it is installed spaced apart by the predetermined distance from the lower chord member 26.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, each of the upper anchor heads 34 may be installed spaced apart by the predetermined distance from the upper chord member 24 by the upper spacer 32 fixed at a lower side thereof to the upper chord member 24 and fixed at an upper side thereof to the upper anchor head 34. In addition, each of the lower anchor heads 44 may be installed spaced apart by the predetermined distance from the lower chord member 26 by the lower spacer 42 fixed at an upper side thereof to the lower chord member 26 and fixed at a lower side thereof to the lower anchor head 44.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, the upper spacer 32 may be fixed to the upper panel point 31 where the upper chord member 24 and the connection member 21 are joined to each other, and the lower spacer 42 may be fixed to the lower panel point 41 where lower chord member 26 and the connection member 21 are joined to each other.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, the horizontal cross-sectional area of each of the upper anchor heads 34 may be formed to be equal to 7-14 times that of the upper spacer 32, and the horizontal cross-sectional area of each of the lower anchor heads 44 may be formed to be equal to 7-14 times that of the lower spacer 42.

Advantageous Effects

The truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention has a structure in which upper and lower anchor heads 34 and 44 are mounted at the upper and lower sides of a truss 20 including an upper chord member 24 and a lower chord member 26 which are connected with each other by the connection members 21. Thus, the upper anchor head 34 and the upper chord member 24 perform a double anchorage function at the upper side of the shear reinforcement device, and the lower anchor head 44 and the lower chord member 26 perform a double anchorage function at the lower side of the shear reinforcement device, so that shear resistance and ductility of the inventive shear reinforcement device is further improved as compared to the conventional prior art. Particularly, the conventional shear reinforcement device has a limitation in that a shear reinforcement range must be reduced by the coating thickness of the shear reinforcement device and the thickness of the members, thereby deteriorating the reinforcement performance. On the other hand, the inventive truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof has an advantage in that since a vertical shear reinforcement range is covered up to the entire range except the concrete coating thickness, the shear reinforcement performance can be maximized. In addition, the inventive truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof can further achieve a confining effect in the longitudinal direction, i.e., in the direction of an X axis through the truss, and is excellent in its own bending resistance. Moreover, the upper side of the shear reinforcement device in which the upper anchor heads 34 are mounted and the lower side of the shear reinforcement device in which lower anchor heads 44 are mounted are in a symmetrical relationship, so that the shear reinforcement device has a very stable reinforcement performance against the stress reversal of the shear reinforcement portion due to an earthquake load, and the like. Besides, the inventive shear reinforcement device does not produce any interference with the reinforcing bars placed in concrete, thereby further improving constructionability. In addition, the function of the spacers 32 and 42 for adjusting the placement position and distance of the reinforcing bars is performed automatically, and thus the reinforcing bars can be placed at more accurate positions through the height adjustment of the truss 20, thereby shortening the construction period while effectively improving construction quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows perspective views of shear reinforcement devices used to increase the shear performance of the joints between slabs and columns in a reinforced concrete structure.

FIG. 2 shows views for explaining problems occurring at the time of installation and stress reversal of the shear reinforcement devices shown in FIG. 1.

FIG. 3 is a view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a technical spirit of the present invention.

FIG. 4 shows views illustrating applicable forms of a truss in the shear reinforcement device of FIG. 3.

FIG. 5 shows views for explaining the confining effect of a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention.

FIG. 6 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention.

FIG. 7 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to another preferred embodiment of the present invention.

FIG. 8 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to still another preferred embodiment of the present invention.

FIG. 9 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to yet another preferred embodiment of the present invention.

FIG. 10 shows views for explaining various examples of an anchor head in a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention.

FIG. 11 is a view illustrating an example in which a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention is typically applied to a reinforced concrete structure.

FIG. 12 is a view illustrating an example in which a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention is applied to a joint where a slab and a column are joined to each other.

FIGS. 13 to 15 are views illustrating examples of prefabrication of reinforcing bars using a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 3 is a view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a technical spirit of the present invention, and FIG. 4 shows views illustrating applicable forms of a truss in the shear reinforcement device of FIG. 3.

Referring to FIG. 3, a shear reinforcement device 10 according to a technical spirit of the present invention includes double anchorage functions at upper and lower sides thereof and is installed in a reinforced concrete structure to increase resistance against shear failure. That is, the shear reinforcement device 10 according to the present invention is configured such that a plurality of upper anchor heads 34 and a plurality of lower anchor heads 44 are mounted at the upper and lower sides of a truss 20 including an upper chord member 24 and a lower chord member 26 which are connected with each other by a plurality of connection members 21. Thus, the respective anchor heads 34 and 44 serves as a primary anchorage means, and the upper chord member 24 and the lower chord member 26 serves as a secondary anchorage means to perform double anchorage functions at the upper and lower sides of the shear reinforcement device 10.

In such a shear reinforcement device 10 according to the present invention, the truss 20 includes the upper chord member 24, the lower chord member 26, and a plurality of connection members 21 for interconnecting the upper chord member 24 and the lower chord member 26.

The truss 20 has a function of a bar-support which enables upper and lower main reinforcing bars and sub reinforcing bars to be tied on the upper chord member 24 or the lower chord member 26 by tie wires within a concrete structure in which the truss is installed together at a joint between a slab and a column. In addition, the truss 20 has a function of a structure device capable of supporting a load when lifting the prefabricated re-bars in the prefabrication of reinforcing bars. For this reason, the shear reinforcement device 10 according to the present invention enables the prefabrication of reinforcing bars as shown in FIG. 13 showing an example of prefabrication of reinforcing bars for a column and FIG. 14 showing an example of prefabrication of reinforcing bars for a beam so that it is possible to expect an effect of reducing the construction period.

In this case, as shown in FIGS. 3 and 4, each of the connection members 21 of the truss 20 may be configured in such a fashion as to selectively apply the vertical member 22 and the diagonal member 23. The vertical member 22 is formed at an upper portion thereof with an upper panel point 31 where the upper chord member 24 and the vertical member 22 are joined to each other, and are formed at a lower portion thereof with a lower panel point 41 where the lower chord member 26 and the vertical member 22 are joined to each other, in such a fashion that the upper panel point 31 and the lower panel point 41 of the vertical member 22 are vertically aligned. In addition, the diagonal member 23 is formed at an upper portion thereof with an upper panel point 31 where the upper chord member 24 and the diagonal member 23 are joined to each other, and are formed at a lower portion thereof with a lower panel point 41 where the lower chord member 26 and the diagonal member 23 are joined to each other, in such a fashion that the upper panel point 31 and the lower panel point 41 of the diagonal member 23 are diagonally aligned.

The connection member 21 preferably is configured to include the vertical member 22 and the diagonal member 23 simultaneously, but may be configured to include any one of the vertical member 22 and the diagonal member 23 depending on the need of designers and users as in a preferred embodiment of the present invention. The structure of the connection member 21 may be modified and applied in various forms through application of relevant techniques in the art to which the present invention pertains without departing from the technical spirit of the present invention. For example, the truss refers to a structure in which one or more members are arranged in a triangular shape, and is a framework of completely performing a function of the structure. The truss can be classified into a simple truss, a compound truss, and a complex truss depending on its shape. The truss 20 according to the present invention may be configured in various forms without departing from the technical spirit of the present invention. In addition, as shown in FIG. 4( c), in the case where the truss is composed of only the upper chord member 24, the lower chord member 26, and the vertical member 22, it is called a referred to as a Vierendeel truss. The Vierendeel truss, which is commonly used in Europe, is connected with rigid panel points, and thus is a Rahmen structure rather than the truss. Nevertheless, the Vierendeel truss is treated to be included in a range of the truss in the present invention.

Meanwhile, in the shear reinforcement device 10 according to the present invention, each of the upper anchor heads 34 is fixedly connected with the upper chord member 24 of the truss 20 at the upper side of the truss 20, and each of the lower anchor heads 44 is fixedly connected with the lower chord member 26 of the truss 20 at the lower side of the truss 20. The upper anchor head 34 and the lower anchor head 44 are installed spaced apart by the predetermined distance from the upper anchor member 24 and the lower anchor member 26 by means of upper and lower spacers 32 and 42 as in the preferred embodiments shown in FIGS. 6 to 8. In this case, the predetermined distance is preferably a distance which allows the upper and lower anchor heads 34 and 44 to be placed at the positions of the upper and lower main reinforcing bars 4 and 5, i.e., the positions of satisfying the specified concrete coating thicknesses L1 and L2 within a concrete structure, specifically a slab 1 as shown in FIGS. 3 and 10. Of course, the upper anchor head 34 and the lower anchor head are preferably formed integrally with the truss 20 together with the spacers 32 and 42, but may be configured in various forms to provide diversity and convenience of its manufacture as in the preferred embodiments of the present invention.

The upper and lower spacers 32 and 42, which allow the upper and lower anchor heads 34 and 44 to be fixed to the upper chord member 24 and the lower chord member 26 at the predetermined distance, function to secure spaces for accommodating the placement of the upper and lower main reinforcing bars 4 and 5 and the upper and lower sub reinforcing bars 4′ and 5′. In addition, the upper and lower spacers 32 and 42 function to adjust the outermost positions of the reinforcing bars, i.e., the positions of satisfying the specified concrete coating thicknesses L1 and L2 and the outermost positions of the anchor heads at the same time. Thus, the lengths of the upper and lower spacers 32 and 42 to which the upper and lower anchor heads 34 and 44 are joined are adjusted depending on the depth needed for placement of the upper and lower reinforcing bars. That is, the upper spacer 32 is adjusted in length to correspond to a sum of the diameters of the two upper main and sub reinforcing bars 4 and 4′ to facilitate the accommodation of the upper main reinforcing bar 4 and the upper sub reinforcing bar 4′. In addition, the lower spacer 42 is adjusted in length to correspond to a sum of the diameters of the two lower main and sub reinforcing bars 5 and 5′ to facilitate the accommodation of the lower main reinforcing bar 5 and the lower sub reinforcing bar 5′. By virtue of the configuration of the upper and lower spacers 32 and 42, the ends of the upper and lower anchor heads 34 and 44 and the ends of the upper and lower outermost reinforcing bars are placed side by side, so that uniform construction quality can be easily secured.

In the shear reinforcement device 10 according to the present invention, the upper and lower anchor heads 34 and 44, and the upper and lower spacers 32 and 42 are preferably installed in a symmetrical pattern with respect to their central axes. That is, if the upper and lower anchor heads 34 and 44, or the upper and lower spacers 32 and 42 are biased with respect to their central axes, a bending stress may occur excessively, thereby resulting in a deterioration of the entire performance of the shear reinforcement device 10. In this case, the central axes of the upper and lower anchor heads 34 and 44, or the upper and lower spacers 32 and 42 coincide with the central axes of the panel points 31 and 31 (see FIG. 3) where the upper chord member 24 and the lower chord member 26 are connected with the connection members 21. In addition, the upper and lower spacers 32 and 42 are preferably joined to the panel points 31 and 41 (see FIG. 3) of the upper chord member 24 and the lower chord member 26 of the truss 20. If the upper and lower spacers 32 and 42 are not joined to the panel points 31 and 41 of the upper chord member 24 and the lower chord member 26 of the truss 20, an additional bending stress occurs to deteriorate the structure performance of the truss.

FIG. 5 shows views for explaining the confining effect of a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention. In FIG. 5, the dotted lines indicate the schematic compressive stress trajectories of the concrete structure against the shear reinforcement device.

Referring to FIG. 5, it can be seen that the truss-type shear reinforcement device 10 having double anchorage functions at upper and lower sides thereof according to the present invention confines the concrete in a direction of Y axis, i.e., in an arrow direction as shown in FIG. 5( a). That is, in the truss-type shear reinforcement device 10 having double anchorage functions at upper and lower sides thereof according to the present invention, since the truss 20 confines the behavior of the concrete occurring in the direction of Y axis, an additional concrete shear reinforcement effect is generated. Particularly, it can be seen that this confinement of the shear reinforcement device 10 produces a larger shear reinforcement effect when the diagonal member 23 is applied as the connection member 21 as shown in FIG. 5( c)<

In addition, it can be seen that the truss-type shear reinforcement device 10 having double anchorage functions at upper and lower sides thereof according to the present invention confines the concrete in a direction of X axis, i.e., in an arrow direction as shown in FIG. 5( b). That is, since the truss-type shear reinforcement device 10 having double anchorage functions at upper and lower sides thereof according to the present invention includes a first and secondary anchorage means in the direction of X axis, the shear resistance performance is improved. In this case, the primary anchorage means includes the upper and lower anchor heads 34 and 44, and the secondary anchorage means includes the upper chord member 24 and the lower chord member 26. In particular, since ductility is improved to greatly alleviate the brittle behavior of concrete in shear failure, stability of the concrete structure against the shear failure is enhanced.

Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to FIGS. 6 to 15.

Meanwhile, the illustration and detailed description of the constitution, operation and effects that can be easily understood from a typical related technique in the art, including a general shear reinforcement device for a reinforced concrete structure and a related technical constitution and action, a construction technique of slabs and columns using the shear reinforcement device, and the like will be made briefly or omitted and only portions related with the present invention will be shown and described.

FIG. 6 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention, FIG. 7 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to another preferred embodiment of the present invention, FIG. 8 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to still another preferred embodiment of the present invention, FIG. 9 is a perspective view illustrating a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to yet another preferred embodiment of the present invention, and FIG. 10 shows views for explaining various examples of an anchor head in a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention.

Referring to FIGS. 6 to 9, the truss-type shear reinforcement device 10 having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention is configured such that a plurality of upper anchor heads 34 and a plurality of lower anchor heads 44 are mounted at the upper and lower sides of a truss 20 including an upper chord member 24 and a lower chord member 26 which are connected with each other by a plurality of connection members 21 according to a technical spirit of the present invention. Thus, the respective anchor heads 34 and 44 serves as a primary anchorage means, and the upper chord member 24 and the lower chord member 26 serves as a secondary anchorage means to perform double anchorage functions at the upper and lower sides of the shear reinforcement device 10. In this case, the truss 20, the upper and lower anchor heads 34 and 44, and the upper and lower spacers 32 and 42 allowing the upper and lower anchor heads 34 and 44 to be fixedly connected to the truss 20 may be configured in various forms as shown in FIGS. 6 to 9.

Referring to FIG. 6, the shear reinforcement device 10 shown in this embodiment applies the vertical member 22 and the diagonal member 23 as the connection member 21 of the truss 20, and the vertical member 22 and the diagonal member 23 are fastened to each other by bolts. Of course, fastening structures of various forms such as welding, riveting, and the like may be applied. In this case, the upper and lower spacers 32 and 42 allowing the upper and lower anchor heads 34 and 44 to be fixedly connected to the truss 20 are formed integrally with the vertical member 22 as the connection member 21. That is, the upper and lower spacers 32 and 42 have the functions of the vertical member 22 of the truss 20 and the upper and lower spacers 32 and 42 using a sheet. The upper spacer 32 is formed in such a fashion as to protrudingly extend upwardly from the top of the upper chord member 24 by a predetermined distance, and the lower spacer 42 is formed in such a fashion as to protrudingly extend downwardly from the bottom of the lower chord member 26 by a predetermined distance. Thus, the upper anchor head 34 is joined to the upper spacer 32 so that it is installed spaced apart by the predetermined distance from the upper chord member 24, and the lower anchor head 44 is joined to the lower spacer 42 so that it is installed spaced apart by the predetermined distance from the lower chord member 26. In this embodiment, there is shown an example of the joining by welding.

In the meantime, the shear reinforcement devices 10 according to this embodiment and other embodiments which will be described later include through-holes 22 a formed at arbitrary positions thereof to increase the bonding force with concrete. In this embodiment, the through-holes formed on the vertical members 22, the diagonal members 21, the upper and lower chord members 24, 26 and the upper and lower anchor heads 34 and 44 are used as holes for assembly, but through-holes except the assembly purpose and the through-holes formed on the upper and lower anchor heads 34 and 44 perform the functions of the through-holes 21 a. Of course, such a configuration for increasing the bonding force with concrete may have the shape of protrusions (e.g., embossing) used variously in the art as well as the shape of the through-holes. Such a configuration may be selectively applied depending on the need.

Further, in FIG. 9, a non-explained reference numeral 70 is another spacer, which functions to automatically adjust the concrete coating thickness when placing the shear reinforcement device 10 on a concrete form at the time of installation of the shear reinforcement device 10 a as shown in FIG. 11( a). Thus, a head 71 of the spacer 70 is set to have the same height as the concrete coating thickness L2 (see FIG. 2).

Referring to FIG. 7, the shear reinforcement device 10 shown in this embodiment applies the vertical member 22 and the diagonal member 23 as the connection member 21 of the truss 20, and the vertical member 22 and the diagonal member 23 are fastened to each other by welding. Of course, fastening structures of various forms such as bolts, rivets, and the like may be applied. In addition, although it is shown in this embodiment that the upper chord member 24, the lower chord member 26, and the vertical members 22 apply a pipe, the present invention is not limited thereto. The shear reinforcement device 10 according to this embodiment is configured such that the upper anchor head 34 is joined to the upper spacer 32 so that it is installed spaced apart by the predetermined distance from the upper chord member 24, and the lower anchor head 44 is joined to the lower spacer 42 so that it is installed spaced apart by the predetermined distance from the lower chord member 26 like the above-mentioned embodiment. Thus, the upper spacer 32 is fixed at a bottom thereof to the upper chord member 24, and is fixed at a top thereof to the upper anchor head 34. In addition, the lower spacer 42 is fixed at a top thereof to the lower chord member 26, and is fixed at a bottom thereof to the lower anchor head 44. Of course, the configurations of the upper anchor head 34 and the upper spacer 32, and the lower anchor heads 44 and the lower spacer 42 may be implemented in various forms. In this embodiment, the shear reinforcement device 10 is configured such that the upper anchor head 34 is formed integrally with the upper spacer 32, and the lower anchor head 44 is formed integrally with the lower spacer 32.

Referring to FIG. 8, the shear reinforcement device 10 shown in this embodiment applies only the vertical member 22 as the connection member 21 of the truss 20, and has a structure in which the upper chord member 24 and the lower chord member 26 of the truss 20 are joined to the vertical member 22 in such a fashion as to inserted into through-holes 22 b formed on the vertical member 22. Herein, the upper chord member 24 and the lower chord member 26 may be configured to be fixed to the vertical member 22 by means of welding. In addition, in this embodiment, the upper anchor heads 34, the upper spacer 32, the vertical member 22, the lower spacer 42, and the lower anchor head 44 are formed integrally with each other.

Referring to FIG. 9, the shear reinforcement device 10 shown in this embodiment applies a wire 23 a and a turnbuckle 23 b as the diagonal member 23 used as the connection member 21 of the truss 20 while having a basic structure of the shear reinforcement device shown in FIG. 7. That is, such a configuration of the diagonal member 23 may be configured in other forms besides fastening means such as weld, bolts, and the like.

Like the various technical configurations shown in FIGS. 6 to 9, the shear reinforcement device 10 according to the present invention may be configured in various forms without departing from the technical spirit of the present invention.

In the meantime, the shear reinforcement device 10 according to a preferred embodiment of the present invention may apply the cross-sectional shapes of the upper and lower anchor heads 34 and 44, and the upper and lower spacers 32 and 42 in various manner as shown in FIG. 10. For example, FIG. 10( a) shows an example in which the upper and lower anchor heads 34 and 44, and the upper and lower spacers 32 and 42 adopt a quadrilateral plate to have the same length in one direction, and FIG. 10( b) shows an example in which the upper and lower spacers 32 and 42 adopt a square bar having a relatively small cross-sectional area as compared to the upper and lower anchor heads 34 and 44 having the quadrilateral plate. In addition, FIG. 10( c) shows an example in which the upper and lower spacers 32 and 42 adopt a circular bar having a relatively small cross-sectional area as compared to that of the upper and lower anchor heads 34 and 44 while the upper and lower anchor heads 34 and 44, and the upper and lower spacers 32 and 42 have a circular cross-sectional area.

In this case, preferably, the horizontal cross-sectional area of the upper anchor head 34 is formed to be equal to 7-14 times that of the upper spacer 32, and the horizontal cross-sectional area of the lower anchor head 44 is formed to be equal to 7-14 times that of the lower spacer 42 in order to secure a sufficient anchorage effect. Limitation of the cross-sectional area of the upper anchor head 34 is based on the proportional relationships of the cross-sectional area which is the most suitable for the stud and the stem, which has been proposed by Abdel-Salam Mokhtar, Amin Ghali and Walter Dilger, et al., in “Stud Shear Reinforcement For Flat Concrete Plates” ACI Structural Journal (technical paper), Title no. 82-60.

FIG. 11 is a view illustrating an example in which a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention is typically applied to a reinforced concrete structure, and FIG. 12 is a view illustrating an example in which a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention is applied to a joint where a slab and a column are joined to each other.

Referring to FIGS. 11 and 12, the shear reinforcement device 10 according to the preferred embodiments of the present invention is installed at a joint where a slab and a column of a reinforced concrete structure are joined to each other or is installed as a substitute for a non-reinforced portion or a stirrup reinforced portion such as a beam, a column, a wall, a foundation, and the like in order to increase resistance against shear failure.

Referring to FIG. 11, a method in which the shear reinforcement device 10 according to the preferred embodiment of the present invention is used in a concrete structure (slab) will be described hereinafter. First, a concrete form is first constructed prior to construction of the slab. In FIG. 11, the details necessary for construction of the slab concrete form are recognized by general technicians, and thus their description will be omitted and only a state in which the sheet of a final sub concrete form is installed is shown.

Next, the lower main reinforcing bar 5 and the lower sub reinforcing bar 5′ are installed. At this time, a plurality of spacers 70′ is typically embedded at regular intervals below the lower main reinforcing bar 5 to secure the concrete coating thickness L2 (see FIG. 3) of the reinforcing bars. In this case, the concrete coating thickness L2 is required to be equal to more than 2 cm in case of the slab. Of course, the shear reinforcement device 10 according to the present invention can secure the concrete coating thickness through installation of the dedicated spacers 70 to improve convenience of the work as described above.

In addition, as shown in FIGS. 11( a) and 11(b), the shear reinforcement device 10 according to the preferred embodiment of the present invention is installed above the lower reinforcing bars. In this case, for the shear reinforcement device 10 according to the preferred embodiment of the present invention, since the lower chord member 26 may be placed on the lower reinforcing bars, there occurs no interference the shear reinforcement device 10 and the reinforcing bars, and the requirements of the concrete coating thickness can be easily satisfied during the construction of the shear reinforcement device 10.

Subsequently, the upper main reinforcing bar 4 and the upper sub reinforcing bar 4′ are installed. In this case, when the upper reinforcing bar is placed on the upper chord member 24 of the shear reinforcement device 10 installed at the previous step, the upper chord member 24 coincides with the placement height of the upper reinforcing bar, so that a worker need not do any other work to secure the concrete coating thickness L1 (see FIG. 3) of the upper reinforcing bar.

The construction method performed by using the shear reinforcement device 10 according to the present invention is significantly excellent in constructionability and has a high accuracy in bar placement as compared to the conventional shear reinforcement device, thereby improving construction quality. That is, the shear reinforcement device 10 according to the present invention is intended to first construct the lower reinforcing bars (including the main reinforcing bar and the sub reinforcing bar: the embedded spacer) on the concrete form. On the other hand, the conventional shear reinforcement device (i.e., the shear stud shown in FIG. 1 (b)) is first required to be placed on the concrete form, and then requires that the lower reinforcing bars (i.e., the main reinforcing bar and the sub reinforcing bar) are placed thereon. At this time, the conventional shear reinforcement device entails a problem in that a worker suffers from an inconvenience of having of paying a special attention to the shear reinforcement device to prevent the shear reinforcement device from falling down or being displaced in the placement of the shear reinforcement device. Further, such a conventional shear reinforcement device has a disadvantage in that since the placement position of the lower reinforcing bar 5 is higher than that in shear reinforcement device 10 according to the present invention by the lower thickness of the shear reinforcement device (see FIG. 2( b)), the bending performance of the structure cured later is relatively deteriorated as compared to that of the shear reinforcement device 10 according to the present invention. Moreover, in the construction method using the conventional shear reinforcement device according to the prior art, since the placement height of the upper reinforcing bars (i.e., the main reinforcing bar and the sub reinforcing bar) cannot be confirmed, separate spacers for placing the upper reinforcing bars are required to be installed. On the other hand, since the shear reinforcement device 10 according to the present invention has its own function of the spacers, its construction is performed in a convenient and rapid manner, and accurate bar placement quality is secured.

Referring to FIG. 12, the placement of the shear reinforcement device at the slab-column joints does not cause interference between the shear reinforcement device and the column since it doe not pass through the column. In addition, as described above, there also occurs no interference between the shear reinforcement device 10 according to the present invention and the reinforcing bars in the slab. The shear reinforcement device 10 according to the present invention also serves as the spacer with respect to the slab reinforcing bars, thereby providing convenience of construction.

As such, the shear reinforcement device 10 according to the preferred embodiment of the present invention allows the upper and lower reinforcing bars placed to be disposed at the outermost position where the concrete coating thickness is secured, and simultaneously performs a shear reinforcement, so that the bending resistance of the reinforced concrete structure can be secured maximally. Further, there occurs a stress reversal phenomenon in which a tensioned portion and a compressed portion are reversed upon the exertion of a lateral load such as earthquake, and the like on the reinforced concrete structure. However, the shear reinforcement device 10 according to the preferred embodiment of the present invention can always maintain a uniform shear reinforcement function by virtue of symmetricity of elements in the vertical direction, thereby resulting in improved stability of the shear reinforcement performance.

FIGS. 13 to 15 are views illustrating examples of prefabrication of reinforcing bars using a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to a preferred embodiment of the present invention, in which FIG. 13 shows an example of prefabrication of reinforcing bars for a column formed by joining a plurality of shear reinforcement device 10 to each other, FIG. 14 shows an example of prefabrication of reinforcing bars for a beam joined with the concrete form, and FIG. 15 shows an example of prefabrication of reinforcing bars using wires and turnbuckles.

Referring to FIGS. 13 to 15, the shear reinforcement device 10 according to the preferred embodiment of the present invention has an its own excellent bending stiffness by virtue of the features of the truss and a further excellent bending stiffness in a state of being tied with the reinforcing bars. As a result, the inventive shear reinforcement device 10 enables prefabrication of reinforcing bars by joining a plurality of shear reinforcement devices in the form of a column or a beam. Therefore, the shear reinforcement device 10 according to the present invention is used as a substitute for a stirrup used in an existing traditional prefabrication of reinforcing bars so as to prefabricate the main reinforcing bars together, which makes it possible to be utilized as a novel prefabrication of reinforcing bars

While the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the preferred embodiments of the present invention has been described and illustrated in connection with specific exemplary embodiments with reference to the accompanying drawings, it will be readily appreciated by those skilled in the art that it is merely illustrative of the preferred embodiments of the present invention and various modifications and changes can be made thereto within the technical spirit and scope of the present invention.

MODE FOR INVENTION

In one exemplary embodiment of the present invention, there is provided a truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, which is installed in a reinforced concrete structure to increase resistance against shear failure, characterized in that the truss-type shear reinforcement device includes:

a truss 20 including an upper chord member 24, a lower chord member 26, and one or more connection members 21 for interconnecting the upper chord member 24 and the lower chord member 26;

one or more upper anchor heads 34 fixedly connected with the upper chord member 24 of the truss 20 at the upper side of the truss 20; and

one or more lower anchor heads 44 fixedly connected with the lower chord member 26 of the truss 20 at the lower side of the truss 20.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, each of the connection members 21 may include any one of a vertical member 22 and a diagonal member 23. The vertical member 22 may be formed at an upper portion thereof with an upper panel point 31 where the upper chord member 24 and the vertical member 22 are joined to each other, and are formed at a lower portion thereof with a lower panel point 41 where the lower chord member 26 and the vertical member 22 are joined to each other, in such a fashion that the upper panel point 31 and the lower panel point 41 of the vertical member 22 are vertically aligned. In addition, the diagonal member 23 may be formed at an upper portion thereof with an upper panel point 31 where the upper chord member 24 and the diagonal member 23 are joined to each other, and are formed at a lower portion thereof with a lower panel point 41 where the lower chord member 26 and the diagonal member 23 are joined to each other, in such a fashion that the upper panel point 31 and the lower panel point 41 of the diagonal member 23 are diagonally aligned.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, each of the connection members 21 may include an upper spacer 32 protrudingly extending upwardly from the top of the upper chord member 24 by a predetermined distance, and a lower spacer 42 protrudingly extending downwardly from the bottom of the lower chord member 26 by a predetermined distance.

In addition, each of the upper anchor heads 34 may be joined to the upper spacer 32 so that it is installed spaced apart by the predetermined distance from the upper anchor member 24,

and each of the lower anchor heads 44 may be joined to the lower spacer 42 so that it is installed spaced apart by the predetermined distance from the lower chord member 26.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, each of the upper anchor heads 34 may be installed spaced apart by the predetermined distance from the upper chord member 24 by the upper spacer 32 fixed at a lower side thereof to the upper chord member 24 and fixed at an upper side thereof to the upper anchor head 34.

In addition, each of the lower anchor heads 44 may be installed spaced apart by the predetermined distance from the lower chord member 26 by the lower spacer 42 fixed at an upper side thereof to the lower chord member 26 and fixed at a lower side thereof to the lower anchor head 44.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, the upper spacer 32 may be fixed to the upper panel point 31 where the upper chord member 24 and the connection member 21 are joined to each other,

and the lower spacer 42 may be fixed to the lower panel point 41 where lower chord member 26 and the connection member 21 are joined to each other.

In the truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention, the horizontal cross-sectional area of each of the upper anchor heads 34 may be formed to be equal to 7-14 times that of the upper spacer 32,

and the horizontal cross-sectional area of each of the lower anchor heads 44 may be formed to be equal to 7-14 times that of the lower spacer 42.

INDUSTRIAL APPLICABILITY

The truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof according to the present invention is installed at a foundation of a reinforced concrete structure, a slab, and a portion where a wall and a slab column are joined to each other so that applicable examples of various forms proposed in the preferred embodiments of the present invention can be applied either alone or combinedly to increase resistance against shear failure. 

1. A truss-type shear reinforcement device having double anchorage functions at upper and lower sides thereof, which is installed in a reinforced concrete structure to increase resistance against shear failure, wherein the truss-type shear reinforcement device comprises: a truss including an upper chord member, a lower chord member, and one or more connection members for interconnecting the upper chord member and the lower chord member; one or more upper anchor heads fixedly connected with the upper chord member of the truss at the upper side of the truss; and one or more lower anchor heads fixedly connected with the lower chord member of the truss at the lower side of the truss.
 2. The truss-type shear reinforcement device according to claim 1, wherein each of the connection members comprises any one of a vertical member and a diagonal member, wherein the vertical member is formed at an upper portion thereof with an upper panel point where the upper chord member and the vertical member are joined to each other, and are formed at a lower portion thereof with a lower panel point where the lower chord member and the vertical member are joined to each other, in such a fashion that the upper panel point and the lower panel point of the vertical member are vertically aligned, and wherein the diagonal member is formed at an upper portion thereof with an upper panel point where the upper chord member and the diagonal member are joined to each other, and are formed at a lower portion thereof with a lower panel point where the lower chord member and the diagonal member are joined to each other, in such a fashion that the upper panel point and the lower panel point of the diagonal member are diagonally aligned.
 3. The truss-type shear reinforcement device according to claim 2, wherein each of the connection members comprises an upper spacer protrudingly extending upwardly from the top of the upper chord member by a predetermined distance, and a lower spacer protrudingly extending downwardly from the bottom of the lower chord member by a predetermined distance, wherein each of the upper anchor heads is joined to the upper spacer so that it is installed spaced apart by the predetermined distance from the upper chord member, and wherein each of the lower anchor heads is joined to the lower spacer so that it is installed spaced apart by the predetermined distance from the lower chord member.
 4. The truss-type shear reinforcement device according to claim 2, wherein each of the upper anchor heads is installed spaced apart by the predetermined distance from the upper chord member by the upper spacer fixed at a lower side thereof to the upper chord member and fixed at an upper side thereof to the upper anchor head, and wherein each of the lower anchor heads is installed spaced apart by the predetermined distance from the lower chord member by the lower spacer fixed at an upper side thereof to the lower chord member and fixed at a lower side thereof to the lower anchor head.
 5. The truss-type shear reinforcement device according to claim 4, wherein the upper spacer is fixed to the upper panel point where the upper chord member and the connection member are joined to each other, and the lower spacer is fixed to the lower panel point where lower chord member and the connection member are joined to each other.
 6. The truss-type shear reinforcement device according to claim 3 wherein the horizontal cross-sectional area of each of the upper anchor heads is formed to be equal to 7-14 times that of the upper spacer, and wherein the horizontal cross-sectional area of each of the lower anchor heads is formed to be equal to 7-14 times that of the lower spacer.
 7. The truss-type shear reinforcement device according to claim 4 wherein the horizontal cross-sectional area of each of the upper anchor heads is formed to be equal to 7-14 times that of the upper spacer, and wherein the horizontal cross-sectional area of each of the lower anchor heads is formed to be equal to 7-14 times that of the lower spacer.
 8. The truss-type shear reinforcement device according to claim 5 wherein the horizontal cross-sectional area of each of the upper anchor heads is formed to be equal to 7-14 times that of the upper spacer, and wherein the horizontal cross-sectional area of each of the lower anchor heads is formed to be equal to 7-14 times that of the lower spacer. 